Could our minds be tricked into satisfying our stomachs?
13 July 2010
The key to losing weight could lie in manipulating our beliefs about how filling we think food will be before we eat it, suggesting that portion control is all a matter of perception.
BBSRC-funded studies showed that participants were more satisfied for longer periods of time after consuming varying quantities of food when they were led to believe that portion sizes were larger than they actually were.
Memories about how satisfying previous meals were also played a causal role in determining how long they staved off hunger. Together, these results suggest that memory and learning play an important role in governing our appetite.
In the first experiment, participants were shown the ingredients of a fruit smoothie. Half were shown a small portion of fruit and half were shown a large portion. They were then asked to assess the 'expected satiety' of the smoothie and to provide ratings before and three hours after consumption. Participants who were shown the large portion of fruit reported significantly greater fullness, even though all participants were given the same quantity of fruit.
In a second experiment, researchers manipulated the 'actual' and 'perceived' amount of soup that people thought that they had consumed. Using a soup bowl connected to a hidden pump beneath the bowl, the amount of soup in the bowl was increased or decreased as participants ate, without their knowledge. 3 hours after the meal, it was the perceived (remembered) amount of soup in the bowl and not the actual amount of soup consumed that predicted post-meal hunger and fullness ratings.
The findings, which will be presented by researchers from the University of Bristol at this month's annual conference of the Society for the Study of Ingestive Behaviour (SSIB), could have implications for more effective labelling of diet foods.
"The extent to which a food can alleviate hunger is not determined solely by its physical size, energy content, and so on. Instead, it is influenced by prior experience with a food, which affects our beliefs and expectations about satiation. This has an immediate effect on the portion sizes that we select and an effect on the hunger that we experience after eating," said Dr Jeff Brunstrom, Reader in Behavioural Nutrition at Bristol university's Department of Experimental Psychology.
"Labels on 'light' and 'diet' foods might lead us to think we will not be satisfied by such foods, possibly leading us to eat more afterwards," added Dr Brunstrom. "One way to militate against this, and indeed accentuate potential satiety effects, might be to emphasise the satiating properties of a food using labels such as 'satisfying' or 'hunger relieving'."
Notes to editors
The SSIB conference takes place between July 13 and 17. Details about SSIB and the annual meeting can be found at: www.ssib.org/web
The research was funded by the Biotechnology & Biological Sciences Research Council (BBSRC) through its Diet and Health Research Industry Club (DRINC) - a public-private partnership that funds research into how the UK food industry can help us to have healthier diets and address serious public health issues such as obesity, as well as investigating the benefits of bioactive ingredients in food.
BBSRC is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £470M in a wide range of research that makes a significant contribution to the quality of life in the UK and beyond and supports a number of important industrial stakeholders, including the agriculture, food, chemical, healthcare and pharmaceutical sectors.
BBSRC provides institute strategic research grants to the following:
- The Babraham Institute
- Institute for Animal Health
- Institute for Biological, Environmental and Rural Studies (Aberystwyth University)
- Institute of Food Research
- John Innes Centre
- The Genome Analysis Centre
- The Roslin Institute (University of Edinburgh)
- Rothamsted Research
The Institutes conduct long-term, mission-oriented research using specialist facilities. They have strong interactions with industry, Government departments and other end-users of their research.
Aliya Mughal, Public Relations Office, University of Bristol
tel: 01173 317033
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